1. Field of the Invention
The present general inventive concept relates to an encapsulated colorant, a method of preparing the same, and an ink composition including the encapsulated colorant.
2. Description of the Related Art
In inkjet printers, a colorant is a material that selectively absorbs or reflects visible light and exhibits a unique color. Colorants are classified into dyes and pigments.
A dye refers to a colorant which is formed by using a given method to color a material such as fiber, leather, fur, and paper, and has high solar light fastness, washing fastness and abrasion fastness. A pigment refers to microparticles containing a colorant, which are not directly dyed on the surface of a material to be colored, but are attached to the surface of the material using a physical method, such as bonding, to provide a unique color.
Dyes mix with and are dissolved in solvents such as water. However, pigments, in general, are insoluble in solvents such as water and thus, evenly dispersing the pigment microparticles within a solution to permanently stabilize and maintain the dispersed pigment microparticles such that the pigment microparticles are not re-agglomerated is important.
Water-soluble dye-type ink has good long-term storage stability, maintains homogeneity, and has sharp color and brightness, but has poor waterfastness and lightfastness properties.
Pigment-type ink has a high optical density (OD), good fastness to water and light, and relatively low bleeding between colors, but has poor long-term storage stability compared to the dye-type ink. Moreover, a picture printed with pigment-type ink has poor rubbing fastness under dry and wet conditions; that is, resistance to abrasion is low.
In addition, while printing in color (multiple-color printing) with a dye or pigment, bleeding of boundaries between colors may occur, which reduces clarity of the picture.
Therefore, there is a need to develop an ink composition which has good storage stability with respect to water-soluble dye-type inks, along with good water fastness with respect to pigment-type inks, and with enhanced printed gloss and abrasion resistance.
Meanwhile, in order to improve the abrasion resistance of ink, a technique of adding a resin to ink compositions has been suggested. However, the addition of a resin may cause an increase in the ink viscosity, which is undesirable in inkjet printers. Also, a technique of adding resin particles to ink in order to suppress the viscosity increase of the ink has been suggested, but the abrasion resistance cannot be sufficiently improved because the resin particles and the pigment are dispersed separately in the ink.
Therefore, the problems mentioned above cannot be resolved by adding new additives to ink compositions. Thus, there is a need to improve ink composition properties by reforming the colorant.